Mini-slump Cone Research Articles

An investigation of the rheological parameters of slurry composed of ordinary Portland cement, Portland pozzolana cement and Portland slag cement

ABSTRACT This paper compares the rheological parameters of ordinary Portland cement of grade 43 (OPC 43), ordinary Portland cement of grade 53 (OPC 53), Portland pozzolana cement (PPC) and Portland Slag Cement (PSC) to study the thixotropic built. Five slurries with increasing water/cement (w/c) ratios from 0.52 to 0.6 were prepared and examined at resting times of 1 minute, 5 minutes and 10 minutes. Static shear stress (τs), dynamic shear stress (τd) and thixotropic index (β) were studied to analyze the thixotropic built of the slurries. The rheological parameters increase for all the mixes with decreasing w/c ratios and increasing resting times. However, for a w/c ratio greater than 0.60, all the mixes lose their plastic viscosity and the rheological parameters approach non-significant values. The τs and τd values for PPC and PSC pastes are higher than those of the OPC pastes because of the increase in cement fineness and increased rate of structuration and hydration. OPC 53 paste shows high β because of the large extent of reversible thixotropic built. The τs values obtained from the viscometrical tests were then compared the mini slump test values. Results show that the rheological parameters are more consistent than the flow values of the mini slump cone test.

Fresh, Compressive and Direct-Tensile characterization of Engineered Cementitious Composite

A new category of high-performance fiber-reinforced composite broadly known as Engineered Cementitious Composite (ECC) has gained rapid attention in the construction industry in recent years. The exceptional behaviour of ECC, therefore high ductility, toughness, and durability, make it a promising material for various structural applications such as tunnel inner lining, dam and bridge deck slab construction. This investigation aims to study the fresh and mechanical characteristics of ECC, including workability, compressive, and direct tensile strength. A total of 15 ECC mixes are prepared with varying superplasticiser-binder ratio (0.200, 0.225, 0.250, 0.275 and 0.300 %), sand-binder ratio (0.35, 0.40 and 0.45) and a constant water-binder ratio (0.27). The mini-slump cone test was performed to examine the workability of the fresh ECC mixtures. The results showed that using a higher content of the superplasticiser resulted in an upsurge in both the workability of the fresh ECC mixtures and the mechanical strength of ECC, particularly the tensile strength. Apart from this, both the mechanical tests are performed at the 7 and 28 days. As per the results, both the compressive strength and direct tensile strength of ECC are found to be comparatively higher than that of the conventional mix. In conclusion, ECC is an efficient construction material for various structural applications, especially for the latest 3D printing construction techniques. The uniform dispersion of fibers significantly improves the tensile strength and ductility of ECC, making it a suitable material for seismic-resistant structures.

Influence of Nano-SiO2 Content on Cement Paste and the Interfacial Transition Zone.

Nano-SiO2 (NS) is widely used in cement-based materials due to its excellent physical properties. To study the influence of NS content on a cement paste and the interfacial transition zone (ITZ), cement paste samples containing nano content ranging from 0 to 2% (by weight of cement) were prepared, and digital image correlation (DIC) technology was applied to test the mechanical properties. Finally, the optimal NS content was obtained with statistical analysis. The mini-slump cone test showed that, with the help of superplasticizer and ultrasonic treatment, the flowability decreased continuously, as the NS content increased. The DIC experimental results showed that NS could effectively improve the mechanical properties of the cement paste and the ITZ. Specifically, at the content level of 1%, the elastic modulus of cement paste and ITZ was 20.95 GPa and 3.20 GPa, respectively. When compared to that without nanomaterials, the increased amplitude was 73.50% and 90.50%, respectively. However, with the further increase in NS content, the mechanical properties decreased, which was mainly caused by the agglomeration of nanomaterials. Additionally, the NS content did not exhibit a significant effect on the thickness of the ITZ, and its value was maintained at 76.91-91.38 μm. SEM confirmed that NS would enhance the microstructure of both cement paste and ITZ.

Statistical analysis on mechanical behaviour of ternary blended high strength concrete

The growing demand for high strength concrete [HSC] in the construction industry increases the usage of cement, resulting in environmental issues. Recent studies are showing that the utilization of cementitious materials in concrete can effectively reduce the volume of cement. In the present study, ternary blended combinations were prepared using cement, silica fume, and fly ash to attain the HSC. Here, cement was partially replaced by silica fume [2.5, 5, 7.5, and 10%] and fly ash [5, 10, and 15%], respectively. Mini slump cone test was conducted to identify the compatibility of cement paste with polycarboxylate ether [PCE] based superplasticizer. The packing density of aggregates was calculated to reduce the voids and improve the particle distribution in HSC. An experimental investigation was carried out, and the ultimate compressive strength was obtained as 71.55 MPa at 28 days of curing. Multi linear regression analysis was conducted to simulate the mix design for aiding the prediction of compressive strength of the HSC.

Flow Characteristics of Slurry Infiltrated Fibrous Concrete (SIFCON) with Silica Fume and Steel Fibers

SIFCON is one of the newly established buildings substantial. The proportion of silica fume additional was 17.5% through mass of cement in slurry infiltrated fibrous concrete & four various bulk segments of plain mild steel fibres, crimped mild steel fibres and hooked ended mild steel fibers (0, 5, 15, 25 and 35) % were utilized. The examined belongings of fresh slurry infiltrated fibrous concrete were normal slump cone test, reversed slump cone test, mini slump cone trial, J- fibres penetration test and L-box test test which were agreed out on usual magnitude of slump cones, J-box and L-box respectively at fresh state of SIFCON slurry (mortar). The spread flow diameter for standard slump cone, inverted slump cone and mini slump cone values up to 670mm, 650mm and 175mm respectively were obtained at fresh state of SIFCON slurry (mortar).

Effects of sediment fractions on slump-flow parameters of fine- and coarse-sediment suspensions

• Slump-flow parameters (slump and spread) of fine- and coarse-sediment suspensions are measured using a mini-slump cone. • Effects of fine- and coarse-sediment fractions on the slump-flow parameters are analyzed and empirically formulated by power-law and exponential relations, respectively. • The single- and double-layer models of Roussel and Coussot [22] and Pierre et al. [21], respectively are generalized for a conical-shaped mould in the range of 0 < α ≤ 1 . • The dimensionless slump and spread of fine- and coarse-sediment suspensions are strongly correlated and their empirical relation was compared to the theoretical relations. • The slump-flow parameters and Bingham yield stress exhibit good correlations in both theoretical and empirical analyses, indicating that the slump-flow test may be used to indirectly evaluate the rheology of sediment suspensions. Slump-flow tests on concentrated fine-sediment suspensions (mixtures of clay-silt-water) and coarse-sediment suspensions (mixtures of coarse sediments and a specified fine-sediment suspension) were performed to investigate the effects of sediment fractions on the slump-flow parameters (slump and spread). The slump and spread of fine- and coarse-sediment suspensions decrease with an increase in the sediment fractions, and their empirical equations were proposed. Both experimental and theoretical results show that the slump and spread of sediment suspensions are strongly correlated. Theoretical relations of the Bingham yield stress and slump-flow parameters were also presented for comparison. The slump-flow parameters exhibit a strong correlation with the rheological parameters measured using a conventional rheometer, indicating that the rheological parameters of the tested sample could be indirectly evaluated by a simple slump-flow test.

The incorporation of recycled brick aggregate in 3D printed concrete

In this paper a more sustainable 3D printable concrete is developed by the replacement of natural aggregate in a concrete mix with recycled brick aggregate (RBA). An existing 3D printable concrete mix is used as reference and adjusted by replacing 64% of its natural aggregate with RBA. The potential for sustainability in the building sector by automation as well as recycling of construction and demolition waste is therefore addressed. To date no research exists on the use of recycled brick aggregate in 3D printed concrete, which has particular relevance in developing countries, where construction with bricks remains a popular option.Two different types of RBA from local demolition projects are considered in three mix designs containing Type 1 RBA, Type 2 RBA and a combination of Type 1 and Type 2 RBA. To arrive at the three mix designs, the water absorption and porosity of each RBA type are first tested to determine the estimated additional water requirement in each concrete mix. The ASTM mini-slump cone test is used as a replacement of a full rheological characterisation to determine the achievement of acceptable printability.After the fresh-state characterisation, the mix design containing the more porous Type 2 RBA is chosen for mechanical characterisation based on availability of materials and relevance of highly porous recycled brick aggregate in future studies. Mechanical characterisation tests are performed on the chosen RBA mix, as well as the reference 3D printable mix for comparison. The mechanical characterisation tests include compressive cube strength tests, direct tensile tests on 3D printed specimens, and uniaxial compressive tests on 3D printed specimens. The results of the mechanical characterisation tests show that the replacement of 64% of the natural aggregate with RBA in the mix reduces the compressive cube strength by 25%, the interlayer tensile 3DPC strength by 20% and the compressive 3DPC strength by 14% and 20% in Direction 1 and Direction 3 respectively.

Taguchi-based interval multi-criteria decision-making method for optimisation of alkali activators

The main purpose of this study is to assess the optimal condition with multiple responses using the Taguchi method in the presence of conformity assessment. For this purpose, all possible arrays, including orthogonal and non-orthogonal arrays, were included in the analysis. The experimental data in the form of interval numbers were directly derived from experimental results for orthogonal arrays, and were computed using the Taguchi prediction method for non-orthogonal arrays. A new pattern of conformity assessment was introduced that eliminates arrays that do not meet the criteria or modifies the interval number of non-orthogonal arrays that meet a part of the criteria. Finally, each accepted array was specified as an alternative, and interval multi-criteria decision-making methods were finally deployed to rank the alternatives. A case study was carried out to find the optimal mixture of sodium silicate activators with strict criteria of ASTM C150 based on the proposed method. To this end, three factors, including the weight percentage of sodium oxide (Na2O) in slag, silicate modulus (SiO2/Na2O), and water to slag (W/S) ratio, each at three levels, were investigated by examining the compressive strength and drying shrinkage of the mortar, along with the setting time and mini-slump cone tests on the fresh paste. Results revealed the effectiveness of the proposed approach and indicated that the Na2O, SiO2/Na2O, and W/S values of 6%, 0.8, and 0.42, respectively, were a reasonable choice for the activator.

Effect of Elevated Temperature on the Properties of Self‐Compacting Mortar Containing Nanomaterials and Zircon Sand

The present research work tries to assess the performance of a self‐compacting mortar containing zircon sand as a substitute for river aggregate in combination with nanoalumina and nanosilica as cement replacements. The fresh state results, as observed through the mini slump cone and mini V funnel, showed positive effects of zircon sand on workability attainment. The EFNARC limits of workability were even satisfied at high substitution levels of the nanoparticle due to the contribution of zircon sand. The mechanical properties, durability, and microstructure of the mortar were evaluated by conducting experiments at room temperature and then at 200°C, 400°C, 600°C, and 800°C. Results show that there was a significant improvement in the thermal stability of the RPC mixes due to the synergistic effect of nanomaterials and zircon sand addition. The addition of nanomaterials and zircon sand accelerated the microstructural buildup and durability at elevated temperatures. The findings thus suggest a novel and effective approach to using zircon sand as a potential alternative to quartz sand in RPC in combination with nanomaterials to produce temperature‐resistant concrete structures.

Study on the fresh and hardened properties of foam concrete incorporating fly ash

A study has been undertaken to examine the fresh state properties and hardened state properties of cellular light weight concrete i.e., foam concrete with fly ash being used as a substitution. The fly ash is replaced at different levels viz., 25%, 50% and 75% by weight of cement. A total of 20 number of mixes were prepared with varying densities ranging from 800 kg/m3 to 1600 kg/m3. For each mix 9 prismatic beam specimens of size 40 mm × 40 mm × 160 mm were cast and tested. Fresh state properties like consistency using mini V-funnel and workability using mini slump cone were determined. The hardened state properties like flexural strength and compressive strength were determined after 7 days and 28 days of age. The consistency i.e., flow time of foam concrete is observed to be decreased with the increase in percentage of fly ash. The workability i.e., slump of foam concrete has increased with the increase in fly ash proportion. The compressive strength and flexural strength have decreased exponentially with the increase in replacement of fly ash.

Investigation on the effect of Colocasia esculenta extract on the fresh properties of cement paste

Currently, the overall concrete development comprises chemical admixtures to change their characteristics, either in their freshen or hardened state. But chemical admixtures may conceivably give off-gases into the indoor air in the buildings. As an alternative to chemical admixtures, admixtures of natural origin i.e., bio-admixtures have been studied by many researchers. This paper is an investigative study of plant extract from Colocasia esculenta on the fresh characteristics of the cement paste. The plant is of wild origin and unproductive to the human need was extracted. The fresh extract from the stem and the leaf part of the Colocasia plant were added in percentages of 1%, 2%, 3%, 4%, and 5% by weight of cement. The variation in the setting time of the cement paste was observed. The outcomes revealed a deduction in the setting time of the cement paste by an increment in the dose of the stem extract and the leaf extract, i.e., tends to decrease the initial setting period and increase the final setting period than the control sample. The workability of a cement paste is measured utilizing the marsh cone flow study and the mini-slump cone test. Both the extracts showed improvement in workability at a 0-minute retention period and thereafter loses their flowability over time due to the accelerating property of the stem extract and viscous nature of the leaf extract. Saturation point was not attained in marsh cone flow graph and hence have to lower the dosage applications.

A study on the setting and flow behaviour of alkali activated slag/fly ash composites in ambient condition

Alkali-activated binders (AAB) are considered as a promising sustainable future construction material, and promoted as an environmentally beneficial option when compared to Ordinary Portland Cement (OPC). Portland cement-based concrete is the most used material in the construction industry. In the production of OPC, harmful gasses like CO2, NO2, SO2 and specks of dust are discharged into the atmosphere due to calcination of limestone and combustion of fossil fuel. Hence in the present scenario, it has become an emphatic necessity to replace Ordinary Portland Cement based concrete with AAB based system (geopolymer) which is more sustainable. The characteristics of geopolymer composites are predominantly influenced by some of the variables such as temperature and time of curing, alkaline solution to solid binder ratio, water content, type of alkaline activators used, molarity of alkaline solution, chemical composition of aluminosilicate precursors etc. Although geopolymer systems are good in terms of durability and strength, the main issue faced for its less popularity in the field application is its low workability, poor slump retention and too fast setting.The aim of this experimental study is to investigate the compatibility between modern generation superplasticizers (SP) and various alkali activated binder systems prepared using industrial wastes and the evaluation on the effect of alkali binder ratio (a/b) on the fresh properties of alkali activated binder (AAB) systems. Considering the practical implications, it is the need of the hour to develop a geopolymer mix setting in ambient condition. This study focuses on setting and flow behaviour of the alkaline activated composites of slag and fly ash in ambient condition only. The slag/fly ash ratios of 100/0, 75/25, 50/50 and 25/75by mass and alkali-to-binder ratios of 0.4 to 1 with an increment of 0.1 were used for the study. The type of superplasticizer used for the study is Sulphonated Naphthalene Formaldehyde (SNF) with dosages of 0%, 1%, 2% and 3%. The setting time and the flow of the paste were determined using vicat apparatus and mini slump cone respectively. The penetration resistance of the setting paste was also measured using vicat apparatus. The test results revealed that even though the setting time increase marginally with SP dosage, the use of SNF was not much effective in prolonging the setting time of alkali activated pastes. There was tremendous increase in the initial and final setting time for pastes with an increase in a/b ratio.

Effectiveness of the rheometric methods to evaluate the build-up of cementitious mortars used for 3D printing

In this study, the effectiveness of different rheometric methods to evaluate the build-up of the cementitious mortars used for 3D printing was investigated. In the first step, 15 paste mixtures proportioned with various dosages of the nanoclay and the high-range water-reducer were made. The optimized paste mixture was then selected to produce 4 mortar mixtures with different quartz sand contents and gradations. The build-up of the mixtures was evaluated using a non-rheometric method, namely mini-slump cone, as well as the rheometric methods, including the static yield stress, and the storage modulus evolutions. Finally, the printing experiments were carried out using a custom-made 3D printer to evaluate the effectiveness of the investigated methods to assess the build-up of the mortars. The results indicated that different testing methods contributed in understanding different aspects of the build-up such as rigidification at rest or under shear. Each of these build-up aspects provided valuable information on the extrudability and the shape stability of the printed layers.

Effect of Carboxylic Density on Sulfate Sensitivity of Polycarboxylate Superplasticizers

Effect of carboxylic density on sulfate sensitivity of polycarboxylate superplasticizers (PCEs) was analyzed. PCEs with different carboxylic densities were synthesized by changing molar ratio of isopropyl oxy polyethylene glycol (TPEG) macro-monomer to acrylic acid. The compositions of the self-synthesized PCEs were tested by 1H nuclear magnetic resonance spectroscopy (1H NMR), and the molecular weight was tested by size exclusion chromatography (SEC). Effects of sulfates on the adsorption-dispersing properties of PCEs and the surface charge of cement system in function of PCEs were investigated through total organic carbon (TOC) analyzer, mini-slump cone, and Zeta potential analyzer. Influence mechanisms of sulfates on the dispersing force of PCEs were evaluated through the competitive adsorption of sulfates, the aggregation of PCEs and the calcium ion concentration in pore solution. The results show that the competitive adsorption between PCE and SO42− impairs the dispersing capability of PCEs. In comparison with calcium sulfate, sodium sulfate has higher negative effects on the dispersing capability of PCEs. High amount of sulfate ions leads to the aggregation of PCEs, which further impairs the dispersing capability of PCEs. PCE with higher carboxylic density is less sensitive to the impact of sulfates.

Effect of water film thickness on the flow in conventional mortars and concrete

Mortar and concrete can be divided into two phases of solids and water, where water fills the voids between the grains and also coats the surface of the particles. The current study investigates the influence of the thickness of coating water on flow spread of mortars and concrete. The article aims at correlating consistency of concrete to consistency of mortar using the concept of excess water layer theory. It was found that the flow behavior of granular mixtures can be directly related to the average water film thickness that envelops the particles. The concept was tested on mortars and concrete mixtures with different cement types, aggregate grading, aggregate shape, fineness and proportioning; proving water film thickness to be the most critical parameter affecting the flow. The results of the study indicate the possibility of predicting the flowability of mixtures by knowing the thickness of the water film that envelops the grains. In addition, the relation between flowability of mixtures measured in different sizes of slump cone is explored to enable translating flow of mortars measured in mini-slump cone to flow of concrete obtained from Abrams’ cone.

Effects of PCEs with various carboxylic densities and functional groups on the fluidity and hydration performances of cement paste

In this research, effects of polycarboxylate superplasticizers (PCEs) with various carboxylic densities and functional groups on the adsorption behavior, dispersing performance as well as hydration characteristics of cement paste were systematically investigated. PCEs with different architectures were synthesized through substituting acrylic groups with sulfonic groups, ester groups, acylamino group, and changing the molar ratio between HPEG and acrylic groups in the PCE backbones under free radical solution polymerization. The molecular structures of different PCEs were characterized by size exclusion chromatography (SEC). The adsorption isotherms and the dispersing properties of different molecular PCEs were measured by total organic carbon measurement (TOC), mini-slump cone and shear rheometer, respectively. Cement hydration characteristics in the function of various molecular PCEs were investigated through X-ray diffraction (XRD), differential thermal analysis-thermogravimetric analysis (DTA-TG) as well as isothermal calorimetry. Results show that carboxylic density and the functional groups in PCE molecules significantly influence the adsorption behavior and the dispersing performance of PCEs. The increase in carboxylic density and integrating sulfonic groups into PCE backbone can enhance the adsorption capability of PCEs onto cement grain surface, which hence generate higher initial dispersing property. PCEs with higher carboxylic density hinder the cement hydration during the induction period, but promote the maximum hydration degree during the acceleration period. Integrating sulfonic group into PCEs backbone significantly promotes the cement hydration, while integrating amide groups or ester groups into the backbone of PCEs depresses the cement hydration process. The variation in cement hydration caused by the addition of different molecular PCEs is almost diminished at 28 d.

Feasibility of using marine sediments in SCC pastes as supplementary cementitious materials

In the context of the depletion of natural geomaterials, the increasing amount of dredged sediments calls for seeking new possibilities for treating and recycling these materials as cementitious supplementary materials. The aim of this paper is to design ecological SCC pastes, which require less cement, incorporating treated marine sediments. Despite many approaches investigating the ultimate formula of self-compacting concrete (SCC), the process remains complex because it is based on many variables and components. According to the mix design method, twenty pastes were prepared with cement, superplasticizer, water, and treated marine sediments from the Dunkirk harbour (France). The pastes’ fresh properties were determined by using the mini-slump cone (workability), and the Marsh cone (fluidity). Rheological properties were determined with a robust rheometer based on the Bingham model. Cohesiveness and compressive strength were tested as well. All responses were connected using ternary diagrams, which led to the definition of an optimal formula. Experimental checking was performed to validate the obtained results.

Fresh and hardened properties of self consolidating Portland limestone cement mortars: Effect of high volume limestone powder replaced by cement

The main purpose of this experimental study is to elucidate the performance of self-compacting mortars (SCMs) composed of high volume limestone powder (LSP). In accordance with this purpose, four different SCMs at which limestone content varied as 0%, 15%, 25% and 35% were designed and later on fresh, hardened and durability properties of the mixtures were investigated for different curing ages depending on the testing method. Compressive strength, splitting tensile strength, rheological properties, mini-slump cone, carbonation, UPV and capillary water absorption were investigated in terms of fresh and hardened performance properties. In term of fresh properties, test results showed that there was a clear increase in the yield stress up to LSP content of 15% and beyond this level there was a tendency of reduction of the yield stress with the increase of limestone addition and also slumps values increased and pointed out a satisfactory fresh property in accordance with the increase in the replacement level of LSP. For mechanical properties, there was a steady decrease in the compressive strength values with the increase in LSP content while the addition of LSP in SCMs more than 15% did not improve splitting tensile strength of the mixtures for all curing ages. As a durability property, carbonation resistance of SCMs samples decreased with the increase in LSP replacement level for all of the mixtures and also UPV values were in an acceptable range of good (for 15%) and doubtful (for 35%) category intervals. Furthermore, the control mixture with the only PC had the lowest sorptivity coefficient as 2.73 cm/s1/2 followed by SCMs with 15%, 25% and 35% LSP as 5.11, 6.13 and 6.14 cm/s1/2, respectively.

Investigations on compatibility of cement-superplasticizer interaction and its influence on mortar workability incorporating copper slag as fine aggregate

Interaction between cement and water is a complex phenomenon to understand. Sometimes achieving the desired results is quite challenging due to the contrast spotted in the characteristics of cement, type and dosage of superplasticizers (S.P) as the behaviour is insignificant. Influence of different types of cement fineness on pastes with different superplasticizers which represents the compatibility between cement with water reducing admixture in order to obtain well-defined saturation dosage and with the partial replacement of fine aggregates (F.A) by copper slag (C.S) to study the mortar behaviour is focused in this work. A methodology based on fundamental properties of cementitious systems using marsh cone and mini-slump cone tests results to identify the suitable and compatible combinations between cement and superplasticizers for the enhancement of flow behaviour of mortar mixes.

Adding granite dust as paste replacement to improve durability and dimensional stability of mortar

In a recent study by the authors, it has been found that the addition of granite dust (GD) as paste replacement (addition of GD to replace an equal volume of cementitious paste with the water/cementitious materials ratio kept constant) to decrease the cementitious paste volume in mortar offers substantial benefits in cement content reduction (and thus carbon footprint reduction), waste utilization, strength improvement and microstructure densification. In this study, the authors extended the research program to evaluate the effects of adding GD as paste replacement on the durability and dimensional stability of mortar. A series of mortar mixes with varying GD volume and water/cement ratio but similar workability achieved by adjusting the superplasticizer dosage were made for mini slump cone test, carbonation test, water absorption test and drying shrinkage test. The test results revealed that adding GD as paste replacement could substantially improve the carbonation and water resistances, reduce the ultimate shrinkage strain and shrinkage rate, and at the same time, reduce the cement content by up to 25%.